Feed screw for stokers



H. E. WINKLER- ET AL June 22', 1948.

FEED SCREWFOR STOKERS Filed 00h 27, 1945 INVENTORS. E lW/VAZE'K.

Patented June 22, 1948 ;-fFEED'sSGREW FOR STKERS Herman" E. Winklergg Lebanon,y Ind., and" "Francis u"EL"BoyerrEast*Grand Rapids, Mich.; asilsignors A-to`U. iSMachine;Corporation, Lebanon; Ind.; a

.a `1 corporation Application'ootobe 27, 1945, Serial No.`"6 24=.992

5 Claims.

1 "'*This nventionrelates toj a' feed screw wfor stokjers whereinsolid fuel, such' as coal.' is screw lfed vfrom a hopper through a` conduitiinto a retort; and ,particularly -v`'to avariabley metering screw Vfor controlling the feed rate per screw revolution inf` accerdance with/the character ,and require- Aments of thefuel.

Ain-stekers employing feed screws, the problems fof; starving the: feed screw, which'` if done to= ex cessfimayilead to smokehack, and overr feeding, 'whichfif excessive may lead'to packingin the -feed tube; andV thereby-docking ofthe feedj screw, are presented. These, problems are affectedhy "theidegreeofcoarseness-V of the solid fuel` being fed;-loylthelengtlfi,0fthey feed screw, or both. Thus, wherein the meteringcapacityof the' screw is fixed by lthefpitch and space between the turns of-"thefflight, V the screw mayv meter properly' for one-coarseness of coalyand vfeed screw lengthgbut improperly-in-respect toothers. For examplain afscrew @having a-"xedf"flight of predetermined capacityfand dameterlinvthev hopper,4 an oversnp'plyisofcoal might be received andlfedinto'the feedltubeif the-coal -is fine, resultingfln packing 'andsfeed screwlo'ckage, whereaswi-th exceedingly coarse coal the soreww'rnight not "be su'iciently lledf-to `offer adequate resistance to prevent the i'flow-1li-gases` from the retort back `through the fedt'ube and hopper'into the atmosphere. v',Thus, with'theifsamef-feed screw; coal can cause 4undue packing fif extrem'ely'iine,v and "if extremen/coarse cause excessivestarving and permitting "smoke back through the hopper.

"Fori-conveniently. and adjustably controlling :the metering:capacity` within-=1thel hopper Ato t: attain the!fdesirecll feed for varyingcoarseness ofl ccal and'fvarylng feed screw length through the freed conduit to: the retort,` an auxiliary metering' flight 'is adjustably-mounted in association.withat fixed ilightfprovided .on thewxed .screw adjacent; :the outletv 'portion of the hopper i leading tto the vfeed conduit. By simpleadjustmentof theauxiliary meteringY flight relative to the fixed iiightof the screw,A .varying metering characteristics are `obtained. Suitable for the varying requirements of coals and lengths.

"The full nature of the invention willbe .understood from the/ accompanying Ydrawings.,and the following'des'criptionV and claims:

""'Figfl'ds acentr'al vertical section "through the hopper lease and# aj portici? of lthe i`eed-coriduit leading; to the retort; and; showing' the `feeclescrew in# elevation "-wilth--i the auxiliary c'metering'l flight positioned-therein.

"-Fig 2=l^is anfeievational'- viewofthe# auxiliary metering flight.

fFigJ 3--isan elevationall viewshowingasection of the f` feedl screw with fthe i metering "flight t#in one position. i

r 4 .is 4lthevsame aslllig 3S showingthef meteringflight ini ai second position.

Fig: 5V -islthesarne as'Fig. 4;"showing the metering flight tin a .'thirrposition.

the draw-ingsflthereieisfshownf in `a fstok'er construction, fa; hoppen-r 9i' having a-Jbase "il El fofithe usual Licharactenfor receiving solid" ueLf-suchi-.as coal. iSaid; lhasei isiimountedi .upon a supportng beanie l I` and fleas` securedzatf th'e endathereoffremote from'theqdishharge; tzr-housing? l 2 Aleading to the driving mechanism for the feedescrew. @The disehargerend roflA the hoppen base' `aperturedi at l 3 opening tinto.; aerusherl block housingl l li-draving a crushergblock lrassociatedwitha removable cover `aplate i l 6 ripreyided with` .ai securing wing bolt `I 'l Communicating-.i with; the; c'rusher ,block housing andffsecuredi [to .the .feedingf end?v thereof there is aa-ijeedf-condnit-f-jlgleadingf to thelusual si-.okervretortL ita..

Extending 4:throug-h.x thefflower; por-tion of the hopper:base;` the? Crusher :block housing and' .feed conduit,V there is a; feed iscrew 2G' ,havingia spiral cast .night f2 I tot@ awpredetermined rv thicknessediameter andfpitch. :The nrear or driving: endeof theffeedrscrewiis vformed with-a socket?! fortreceiizing :1i-drivingshaft VZut-driven from any-.suitablesourceetpower, asiswell understood. ET-he forward. or.feedingende` oi` the screw `terminates in association withgthe.retortwlawto be'ffed in the customarymanner.

AsA shown'fhereimihe first turn-of ther-flight adjacentftheldischarge, aperture` :l S-iothe `hopper base. is` gof ,the .sarna-diameten ande-,pitches .the screw flight leading through thetfee'd conduitfil-S. However, lrearwardly,,thereof and, extending 5toward the remotaor'far. endcf`r the `hopper base .the feed` screw .is .tapered i wherein thediameterf. of the flight is ,gradually reduced iin.` Ldiameter to reducev ree'circulation.

`For`varying the coal receiving or meteringea-` pacity of the feed screw relative to its feed, the

distance between turns of the night at the discharge end of the hopper base is reduced throughout a varying extent of that critical portion of the screw leading from the hopper to the Crusher block l5. This is accomplished by providing an auxiliary metering night 24 shown in Fig. 2, which comprises an auxiliary night of the same pitch and diameter as the last turn of the nxed night 2|.

The metering flight is carried by the screw shaft 20 in association with the nxed night thereof, but is adjustable longitudinally of the screw by relative rotation therewith. For securing the metering night in adjusted position, the second turn of the fixed night from the crusher block is provided with an aperture, indicated at 25, for

registry with one of these corresponding aperf tures indicated at 26, 2l and 28 in the metering night. Said nights are secured together by a bolt and nut 29, clamping them through said apertures when aligned.

When the metering night is in its forwardmost position, as shown in Fig. 1, it is secured to the night 2| through the apertures 25, 25. In this position, due to the taper of the fixed metering screw, its metering capacity is at a minimum, resulting in maximum starving of the feed screw. This position is suitable for nne coal. Thus, a less amount of coal is fed from the hopper base to the feed conduit than the capacity thereof and the feed screw operated therethrough. y

Wherein the coal to be fed is of normal character, the bolt and nut 29 are removed and the metering night 24 is revolved about the shaft 2G to bring the second aperture 21 thereof in registry with the aperture 25 of the fixed night, as shown in Fig. 4. If the coal is very coarse, through the same procedure the metering night may be adjusted to its innermost position about the shafty 20 until the aperture 28 therein is in registry with the aperture 25, as shown in Fig. 5. In all three positions, the metering night is secured by the bolt and nut 29 extending through the aperture 25 and the respective selected apertures of the metering night.

In the latter or innermost position of the meternight, the metering position of the feed screw is increased by reason of the auxiliary metering night being of greater diameter than the tapered portion of the fixed night.

The effect of the metering flight in respect to coal receiving and feeding capacity is illustrated in Figs. 3, 4- and 5, wherein the diameter of the fixed night turns is gradually reduced to provide a taper as compared with the diameter of the turns of the metering night associated therewith, which are constant and of the maxi-l mum diameter of the fixed night. Thus, wherein the metering flight extends into the hopper base only a short distance as in Fig. 1, the receiving capacity of the screw is substantially normal. In the position of Fig. 4, its metering capacity is further increased, and in its extreme inner position of Fig. 5, its metering capacity is at a maximum. It will also be noted that the combined turns of the auxiliary and fixed nights has the effect of increasing the thickness of the effective joint metering night, with a corresponding reduction in space therebetween. In this manner the effective metering of coal, ranging from coarse to fine, is obtained toprevent undue packing of the feed screw in the feed tube on the one hand, and smoke back through the hopper on the other.

Wherein thereis disclosed by way of illustration herein one arrangement for varying the effective feeding capacity of the screw, it is not intended that the invention be limited to said modification, but may embrace other and equivalent arrangements within the scope of the'appended claims.

The invention claimed is:

1. In a stoker having a hopper base for containing a supply of solid fuel and a feed conduit connected with said hopper base, the combination of a feed screw extending through said hopper base and conduit including a rotative shaft and fixed spiral night of predetermined metering capacity, an auxiliary metering night correspond- 4ing to and nesting with a plurality of turns of said fixed night within the hopper base, and means for interlocking said auxiliary metering night with said fixed night at a selected position relative to the discharge end of said hopper base for varying the fuel metering capacity of said feed screw.

2. In a Stoker having a hopper base for containing a supply of solid fuel and a feed conduit connected with said hopper base, the combination of a feed screw extending through said hopper base and conduit including a rotative shaft and fixed spiral night of predetermined metering capacity, an auxiliary metering night corresponding to and nesting with a plurality of turns of said fixed night, said auxiliary metering night being rotatable about the shaft relative to the nxed night of said feed screw to be thereby moved longitudinally thereof into and out of said hopper base for varying the fuel metering capacity of said feed screw, and means for securing said auxiliary flight in a selected position relative to said fixed night.

3. A feed screw for a stoker comprising a rotatable shaft having a fixed spiral flight of predetermined capacity, an auxiliary metering flight corresponding to and nesting with a plurality of turnsof said fixed night adjustable relative thereto, and means for securing said auxiliary flight in a selected position relative to said fixed night.

4. A feed screw for a stoker comprising a rotatable shaft having a nxed spiral night of predetermined capacity, said night having an aperture therein, an auxiliary metering night corresponding to and nesting with a plurality of turns of said fixed night to be rotatable relative thereto for longitudinal adjustment thereon, said metering night being provided with a series of spaced apertures selectively registerable with said aforementioned aperture, and an element extending through said first-mentioned aperture and a registering aperture of said metering night for interlocking said nights. n

5. In a stoker having a hopper base for containing a supply of solid fuel and a feed conduit connected With said hopper base, the combination of a feed screw extending through said hopper base and feed conduit including a rotative shaft and fixed spiral night, predetermined turns of said night within said hopper being of progressively less diameter for tapering away from the discharge end of said hopper base, an auxiliary metering night corresponding in diameter to the maximum diameter of said fixed night and nesting with a plurality of turns thereof adjacent the discharge end of said hopper base, said auxiliary night being rotatable'thereabout to move longitudinally thereof for varying the fuel metering capacity of said feed screw, and means for interlocking said xed flight and metering ight Number in their adjusted relative position. 1,373,748 HERMAN E. WINKLER. 1,553,539 FRANCIS E. BOYER. 1,767,248 5 2,118,289 REFERENCES CITED 2,199,770

The following referenees are of record in the f1 f thi t 1 e o s pa ent 2,343,707

UNITED STATES PATENTS w Number Name 998,048 Thomas July 1a, 1911 Nuglba 1,134,600 Eilson Apr. 6, 1915 18 3 Name Date Lower Apr. 5, 1921 Kinyon Sept. 15, 1925 Leach June 24, 1930 Birkenbeuel May 24, 1938 Young May 7, 1940 Nelson Mar. 4, 1941 Matheis Dec. 16, 1941 Roland Mar. '7, 1944 FOREIGN PATENTS Country Date Germany Feb. 16, 1931 

